Remove GitPod support (#13345)

.gitpod.yml

@@ -1,15 +0,0 @@
-tasks:
-  - init: gem install bundler -v 2.0.1 && bundle install && bundle exec rake generate
-ports:
-  - port: 4000
-    onOpen: open-browser
-github:
-  prebuilds:
-    master: true
-    branches: true
-    pullRequests: true
-    pullRequestsFromForks: true
-    addCheck: true
-    addComment: false
-    addBadge: false
-    addLabel: false

.theia/tasks.json

@@ -1,30 +0,0 @@
-{
-    "tasks": [
-        {
-            "label": "Generate",
-            "type": "shell",
-            "command": "bundle",
-            "args": [
-                "exec",
-                "rake",
-                "generate"
-            ],
-            "options": {
-                "cwd": "${workspaceFolder}"
-            }        
-        },
-        {
-            "label": "Preview",
-            "type": "shell",
-            "command": "bundle",
-            "args": [
-                "exec",
-                "rake",
-                "preview"
-            ],
-            "options": {
-                "cwd": "${workspaceFolder}"
-            }        
-        }
-    ]
-}